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From:   Alim Akhtar <alim.akhtar@gmail.com>
Date:   Mon, 18 Nov 2019 18:53:13 +0530
Message-ID: <CAGOxZ53Z6je9Omuh2k=wVJrGVKZDfsfx6=mUJ-8QiRk-2q3u0g@mail.gmail.com>
Subject: Re: [PATCH v2 4/4] scsi: ufs: Complete pending requests in host reset
 and restore path
To:     Can Guo <cang@qti.qualcomm.com>
Cc:     asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        rnayak@codeaurora.org, linux-scsi@vger.kernel.org,
        kernel-team@android.com, saravanak@google.com,
        Mark Salyzyn <salyzyn@google.com>,
        Can Guo <cang@codeaurora.org>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        Pedro Sousa <pedrom.sousa@synopsys.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Bean Huo <beanhuo@micron.com>,
        Tomas Winkler <tomas.winkler@intel.com>,
        Venkat Gopalakrishnan <venkatg@codeaurora.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>,
        open list <linux-kernel@vger.kernel.org>
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On Mon, Nov 18, 2019 at 9:22 AM Can Guo <cang@qti.qualcomm.com> wrote:
>
> From: Can Guo <cang@codeaurora.org>
>
> In UFS host reset and restore path, before probe, we stop and start the
> host controller once. After host controller is stopped, the pending
> requests, if any, are cleared from the doorbell, but no completion IRQ
> would be raised due to the hba is stopped.
> These pending requests shall be completed along with the first NOP_OUT
> command(as it is the first command which can raise a transfer completion
> IRQ) sent during probe.
> Since the OCSs of these pending requests are not SUCCESS(because they are
> not yet literally finished), their UPIUs shall be dumped. When there are
> multiple pending requests, the UPIU dump can be overwhelming and may lead
> to stability issues because it is in atomic context.
> Therefore, before probe, complete these pending requests right after host
> controller is stopped and silence the UPIU dump from them.
>
> Signed-off-by: Can Guo <cang@codeaurora.org>
> ---

Tested-by: Alim Akhtar <alim.akhtar@samsung.com>

Please add all previous Ack/reviewed and tested-by tags so that we are
aware what need to be done for this patch.
Thanks

>  drivers/scsi/ufs/ufshcd.c | 24 ++++++++++--------------
>  drivers/scsi/ufs/ufshcd.h |  2 ++
>  2 files changed, 12 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 5950a7c..b92a3f4 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -4845,7 +4845,7 @@ static void ufshcd_slave_destroy(struct scsi_device *sdev)
>                 break;
>         } /* end of switch */
>
> -       if (host_byte(result) != DID_OK)
> +       if ((host_byte(result) != DID_OK) && !hba->silence_err_logs)
>                 ufshcd_print_trs(hba, 1 << lrbp->task_tag, true);
>         return result;
>  }
> @@ -5404,8 +5404,8 @@ static void ufshcd_err_handler(struct work_struct *work)
>
>         /*
>          * if host reset is required then skip clearing the pending
> -        * transfers forcefully because they will automatically get
> -        * cleared after link startup.
> +        * transfers forcefully because they will get cleared during
> +        * host reset and restore
>          */
>         if (needs_reset)
>                 goto skip_pending_xfer_clear;
> @@ -6333,9 +6333,15 @@ static int ufshcd_host_reset_and_restore(struct ufs_hba *hba)
>         int err;
>         unsigned long flags;
>
> -       /* Reset the host controller */
> +       /*
> +        * Stop the host controller and complete the requests
> +        * cleared by h/w
> +        */
>         spin_lock_irqsave(hba->host->host_lock, flags);
>         ufshcd_hba_stop(hba, false);
> +       hba->silence_err_logs = true;
> +       ufshcd_complete_requests(hba);
> +       hba->silence_err_logs = false;
>         spin_unlock_irqrestore(hba->host->host_lock, flags);
>
>         /* scale up clocks to max frequency before full reinitialization */
> @@ -6369,7 +6375,6 @@ static int ufshcd_host_reset_and_restore(struct ufs_hba *hba)
>  static int ufshcd_reset_and_restore(struct ufs_hba *hba)
>  {
>         int err = 0;
> -       unsigned long flags;
>         int retries = MAX_HOST_RESET_RETRIES;
>
>         do {
> @@ -6379,15 +6384,6 @@ static int ufshcd_reset_and_restore(struct ufs_hba *hba)
>                 err = ufshcd_host_reset_and_restore(hba);
>         } while (err && --retries);
>
> -       /*
> -        * After reset the door-bell might be cleared, complete
> -        * outstanding requests in s/w here.
> -        */
> -       spin_lock_irqsave(hba->host->host_lock, flags);
> -       ufshcd_transfer_req_compl(hba);
> -       ufshcd_tmc_handler(hba);
> -       spin_unlock_irqrestore(hba->host->host_lock, flags);
> -
>         return err;
>  }
>
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index e0fe247..1e51034 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -513,6 +513,7 @@ struct ufs_stats {
>   * @uic_error: UFS interconnect layer error status
>   * @saved_err: sticky error mask
>   * @saved_uic_err: sticky UIC error mask
> + * @silence_err_logs: flag to silence error logs
>   * @dev_cmd: ufs device management command information
>   * @last_dme_cmd_tstamp: time stamp of the last completed DME command
>   * @auto_bkops_enabled: to track whether bkops is enabled in device
> @@ -670,6 +671,7 @@ struct ufs_hba {
>         u32 saved_err;
>         u32 saved_uic_err;
>         struct ufs_stats ufs_stats;
> +       bool silence_err_logs;
>
>         /* Device management request data */
>         struct ufs_dev_cmd dev_cmd;
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>


-- 
Regards,
Alim